Grab



G. NIEMANN Oct. 20, 1936.

GRAB

Filed Novv 13, 1933 Inventar j.

Attorney.

Patented Oct. 20, 1936 UNITED STATES ATENT OFFICE GRAB many

Application November 13, 1933, Serial No. 697,704 In Germany November 18, 1932 4 Claims.

Considerable difiiculty is involved in fitting the motor driving mechanism within motor-driven grabs. With the common motor-driven grabs which employ a grab-head which at one end are connected by ropes to a supporting beam and at the other end by pressure rods to the halves of the grab, the height of the grab is relatively great and so the use to which such grabs can be put is very considerably limited. If the height be reduced the width between the jaws and also the gripping power are likewise diminished.

The invention relates to a motor-driven grab in which the two advantages, that is to say the increased distance between the jaws and small height, which hitherto have only been obtainable each to the exclusion of the other, can be secured together in one apparatus; this is effected by providing the motor driving gear and the pivots by which this driving gear is connected to the halves of the grab between the pivots upon which the halves of the grab revolve. These pivots'are thus set wide apart and the space between them is utilized for the accommodation of the motor-driven gearing. The motor driving gear therefore does not increase the height of the grab or at any rate increases it by very little, and the halves of the grab lie wide apart in the opened position in consequence of the disposition of their pivots. Thus, the height of the grab is maintained inconsiderable, while the width between the jaws is great and so the dead weight of the grab can be reduced. The whole grab is thus of robust construction and consists of only four elements, that is to say the two halves of the actual grab, the supporting beam and the driving gear.

A grab constructed according to the invention is illustrated, by way of example, in the accompanying drawing.

40 Figure 1 is a side view of a grab partly in section to illustrate the construction of the mechanism; Figure 2 is a detailed view of part of the mechanism.

Referring to the drawing A is the supporting 45 beam or frame and B and C are the two halves of the actual grab. The supporting beam or frame carries the pivots l and 2 of the halves of the grab. The motor 3 and the transmission and reduction gearing l and 4a are mounted between the said pivots. The motor may, however, be replaced by a motor driven gearing. The toothed wheel 4a is secured on a spindle 5, which, for each half of the grab, is surrounded along its length by an internally screw-threaded sleeve 6. Only the extremities or heads I of the spindle 5 are screw-threaded, the spindle 5 being otherwise cylindrical and smooth. Each sleeve 6 is on the other hand provided with a screw thread, the length of which is determined by the required movement of the sleeve in relation to the spindle head. The sleeves 6 are pivoted at 8 and 9 to the halves B and C of the grab. The packing I0 consists of felt or the like which slides on the cylindrical parts of the spindle 5 and therefore can be simply and effectively formed. The motor 3 and gear 4 together represent a driving unit which rides in some measure on the spindle and is carried by it. To prevent the motor 3 from rotating about the spindle 5 instead of the motor rotating the spindle itself a pin is provided on the supporting beam A. This pin is indicated l l and a fork-shaped stop i2 is provided on the gear casing which encloses the tooth wheels 4 and 4a.. The pin ll effectively prevents the stop l2 from rotating in every position of the casing of the motor 3. The gearing is so provided that when the grab is in the opened position the driving unit presses on the supporting beam A so that the spindle 5 is relieved of bending stresses when the lower end of the gearing 3, 4 lies upon the material to be hoisted.

I claim:

1. A motor-driven grab comprising a beam or frame by which the grab is suspended, grab halves, pivot pins connecting said grab halves directly to said beam or frame, a spindle with opposite screw threads, nuts engaging the said spindle and respectively connected to the grab halves, and a motor-operated gearing disposed within the space enclosed by the grab halves and supported upon and serving to rotate the said spindle in opposite directions, the said motor-operated gearing being constrained from revolving about the spindle by contact with the beam or frame.

2. A motor-driven grab comprising a beam or frame by which the grab is suspended, grab halves, pivot pins connecting said grab halves di rectly to said beam or frame, a spindle with oppositely screw-threaded heads provided at the respective ends, sleeve nuts respectively engaging the said screw-threaded spindle heads, the screwthreaded bores of the sleeve nuts corresponding in length to the movement of the screw-threaded spindle heads relatively thereto in the opening and closing movement of the grab, the said sleeve nuts being respectively connected to the grab halves, and a motor-operated gearing formed as a unit disposed within the space enclosed by the grab halves and wholly supported upon the spindie.

3. A motor-driven grab comprising a beam or frame by which the grab is suspended, grab halves, pivot pins connecting said grab halves directly to said beam or frame, a spindle with oppositely screw-threaded heads provided at the respective ends, sleeve nuts respectively engaging the said screw-threaded spindle heads, the screw-threaded bores of the sleeve nuts corresponding in length to the movement of the screw-threaded spindle heads relatively thereto in the opening and closing movement of the grab, the said sleeve nuts being respectively connected to the grab halves, and a motor-operated gearing formed as a unit disposed within the space enclosed by the grab halves and wholly supported upon the spindle, the said motor-operated gearing being constrained from revolving about the spindle by contact with the beam or frame.

in the opening and closing movement of the grab,

the said sleeve nuts being respectively connected to the grab halves, and a motor-operated gearing formed as a. unit disposed within the space enclosed by the grab halves and wholly supported upon the spindle but constrained from revolution relatively thereto, the said sleeve nuts being I closed at the outer ends and the motor unit being provided with packing around the spindle. GUSTAV NIEMANN. 

